Plant-based polyphenols (i.e., phytochemicals) have been used as treatments for human ailments for centuries. The mechanisms of action of these plant-derived compounds are now a major area of ...investigation. Thousands of phytochemicals have been isolated, and a large number of them have shown protective activities or effects in different disease models. Using conventional approaches to select the best single or group of best chemicals for studying the effectiveness in treating or preventing disease is extremely challenging. We have developed and used computational-based methodologies that provide efficient and inexpensive tools to gain further understanding of the anticancer and therapeutic effects exerted by phytochemicals. Computational methods involving virtual screening, shape and pharmacophore analysis and molecular docking have been used to select chemicals that target a particular protein or enzyme and to determine potential protein targets for well-characterized as well as for novel phytochemicals.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Coxibs, including celecoxib, and other nonsteroidal anti-inflammatory drugs (NSAID), including aspirin, are among the most promising cancer chemopreventive agents in development today. This article ...examines the data on the efficacy of these agents in animal model studies of cancer prevention carried out by the authors. The studies evaluated here are restricted to our rodent models of colon/intestinal, bladder, and nonmelanoma skin cancer, in which celecoxib and other NSAIDs were administered as either cancer preventive or therapeutic agents. These studies may shed light on several questions. Is celecoxib unique compared with other NSAIDs, and if so, what implications would this have for human use? Are standard NSAIDs (which inhibit both COX-1 and COX-2) as effective as celecoxib in animal studies? Is the efficacy of celecoxib in particular or NSAIDs in general due to their off-target effects or to their effects on COX-1 and COX-2? What is the likely efficacy of low-dose aspirin? Some questions raised by human trials and epidemiology are discussed and related to our observations in animal model studies. We also discuss the problem of cardiovascular (CV) events associated with coxibs and certain other NSAIDs and whether results in animal models are predictive of efficacy in humans. On the basis of epidemiologic studies and its CV profile, aspirin seems to be the most promising NSAID for preventing human colorectal, bladder, and skin cancer, although the animal data for aspirin are less clear. A comprehensive understanding of the results of coxibs and other NSAIDs in animal studies may help inform and shape human trials of these commonly employed, relatively inexpensive, and highly effective compounds.
Therapeutic targeting of RAS-mutated cancers is difficult, whereas prevention or interception (treatment before or in the presence of preinvasive lesions) preclinically has proven easier. In the A/J ...mouse lung model, where different carcinogens induce tumors with different KRAS mutations, glucocorticoids and RXR agonists are effective agents in prevention and interception studies, irrespective of specific KRAS mutations. In rat azoxymethane-induced colon tumors (45% KRAS mutations), cyclooxygenase 1/2 inhibitors and difluoromethylornithine are effective in preventing or intercepting KRAS-mutated or wild-type tumors. In two KRAS mutant pancreatic models multiple COX 1/2 inhibitors are effective. Furthermore, combining a COX and an EGFR inhibitor prevented the development of virtually all pancreatic tumors in transgenic mice. In the N-nitroso-N-methylurea-induced ER positive rat breast model (50%HRAS mutations) various selective estrogen receptor modulators, aromatase inhibitors, epidermal growth factor receptor inhibitors, and retinoid X receptor agonists are profoundly effective in prevention and interception of tumors with wild type or mutant HRAS, while the farnesyltransferase inhibitor tipifarnib preferentially inhibits HRAS-mutant breast tumors. Thus, many agents not known to specifically inhibit the RAS pathway, are effective in an organ specific manner in preventing or intercepting RAS-mutated tumors. Finally, we discuss an alternative prevention and interception approach, employing vaccines to target KRAS.
Overexpression of nonmutated proteins involved in oncogenesis is a mechanism by which such proteins become immunogenic. We questioned whether overexpressed colorectal cancer associated proteins found ...at higher incidence and associated with poor prognosis could be effective vaccine antigens. We explored whether vaccines targeting these proteins could inhibit the development of intestinal tumors in the azoxymethane (AOM)-induced colon model and APC Min mice.
Humoral immunity was evaluated by ELISA. Web-based algorithms identified putative Class II binding epitopes of the antigens. Peptide and protein specific T-cells were identified from human peripheral blood mononuclear cells using IFN-gamma ELISPOT. Peptides highly homologous between mouse and man were formulated into vaccines and tested for immunogenicity in mice and
tumor challenge. Mice treated with AOM and APC Min transgenic mice were vaccinated and monitored for tumors.
Serum IgG for CDC25B, COX2, RCAS1, and FASCIN1 was significantly elevated in colorectal cancer patient sera compared to volunteers (CDC25B p=0.002, COX-2 p=0.001, FASCIN1 and RCAS1 p<0.0001). Epitopes predicted to bind to human class II MHC were identified for each protein and T-cells specific for both the peptides and corresponding recombinant protein were generated from human lymphocytes validating these proteins as human antigens. Some peptides were highly homologous between mouse and humans and after immunization, mice developed both peptide and protein specific IFN-γ-secreting cell responses to CDC25B, COX2 and RCAS1, but not FASCIN1. FVB/nJ mice immunized with CDC25B or COX2 peptides showed significant inhibition of growth of the syngeneic MC38 tumor compared to control (p<0.0001). RCAS1 peptide vaccination showed no anti-tumor effect. In the prophylactic setting, after immunization with CDC25B or COX2 peptides mice treated with AOM developed significantly fewer tumors as compared to controls (p<0.0002) with 50% of mice remaining tumor free in each antigen group. APC Min mice immunized with CDC25B or COX2 peptides developed fewer small bowel tumors as compared to controls (p=0.01 and p=0.02 respectively).
Immunization with CDC25B and COX2 epitopes consistently suppressed tumor development in each model evaluated. These data lay the foundation for the development of multi-antigen vaccines for the treatment and prevention of colorectal cancer.
Lung cancer is the leading cause of cancer death worldwide. Vaccination against EGFR can be one of the venues to prevent lung cancer. Blocking glutamine metabolism has been shown to improve ...anticancer immunity. Here, the authors report that JHU083, an orally active glutamine antagonist prodrug designed to be preferentially activated in the tumor microenvironment, has potent anticancer effects on EGFR‐driven mouse lung tumorigenesis. Lung tumor development is significantly suppressed when treatment with JHU083 is combined with an EGFR peptide vaccine (EVax) than either single treatment. Flow cytometry and single‐cell RNA sequencing of the lung tumors reveal that JHU083 increases CD8+ T cell and CD4+ Th1 cell infiltration, while EVax elicits robust Th1 cell‐mediated immune responses and protects mice against EGFRL858R mutation‐driven lung tumorigenesis. JHU083 treatment decreases immune suppressive cells, including both monocytic‐ and granulocytic‐myeloid‐derived suppressor cells, regulatory T cells, and pro‐tumor CD4+ Th17 cells in mouse models. Interestingly, Th1 cells are found to robustly upregulate oxidative metabolism and adopt a highly activated and memory‐like phenotype upon glutamine inhibition. These results suggest that JHU083 is highly effective against EGFR‐driven lung tumorigenesis and promotes an adaptive T cell‐mediated tumor‐specific immune response that enhances the efficacy of EVax.
Glutamine blockade with JHU083 enhances the efficacy of an epidermal growth factor receptor (EGFR) peptide vaccine in controlling the development and growth of EGFR‐driven lung cancer. JHU083 increases infiltration of anti‐tumor CD8+ T cells and Th1 T cells and decreases immune suppressive myeloid‐derived suppressor cells, regulatory T cells, and CD4+ Th17 cells in EGFR‐mutated lung tumors.
Hypothetical computational models of Src in complex with kaempferol. Our results suggest that kaempferol is a potent chemopreventive agent against skin cancer through its inhibitory interaction with ...Src.
Ultraviolet (UV) radiation is the primary environmental risk factor in the development of nonmelanoma skin cancer, and UVB in particular promotes tumor growth through various signaling pathways. Kaempferol, a flavonoid with anti-inflammatory and anti-oxidative properties, has been studied as a chemopreventive agent; however, little is known regarding its effects on UVB-induced photo-carcinogenesis. Here, we examined the effect of kaempferol on UVB-induced skin inflammation. We found that kaempferol suppressed UVB-induced cyclooxygenase-2 (COX-2) protein expression in mouse skin epidermal JB6 P+ cells and attenuated the UVB-induced transcriptional activities of
cox-2 and
activator protein-1 (
AP-1). Kaempferol attenuated the UVB-induced phosphorylation of several mitogen-activated protein kinases (MAPKs), including ERKs, p38, and JNKs, but had no effect on the phosphorylation of the upstream MAPK regulator Src. However,
in vitro and
ex vivo kinase assays demonstrated that kaempferol suppressed Src kinase activity. Furthermore,
in vivo data from mouse skin support the idea that kaempferol suppresses UVB-induced COX-2 expression by blocking Src kinase activity. A pull-down assay revealed that kaempferol competes with ATP for direct binding to Src. Docking data suggest that kaempferol docks easily into the ATP-binding site of Src, which is located between the N and the C lobes of the kinase domain. Taken together, these results suggest that kaempferol is a potent chemopreventive agent against skin cancer through its inhibitory interaction with Src.
The sigma-2 receptor is expressed in higher density in proliferating (P) tumor cells versus quiescent (Q) tumor cells, thus providing an attractive target for imaging the proliferative status (i.e., ...P:Q ratio) of solid tumors. Here we evaluate the utility of the sigma-2 receptor ligand 2-(2-(18)Ffluoroethoxy)-N-(4-(3,4-dihydro-6,7-dimethoxyisoquinolin-2(1H)-yl)butyl)-5-methyl-benzamide, (18)FISO-1, in two different rodent models of breast cancer. In the first study, small animal Positron Emission Tomography (PET) imaging studies were conducted with (18)FISO-1 and (18)FDG in xenografts of mouse mammary tumor 66 and tracer uptake was correlated with the in vivo P:Q ratio determined by flow cytometric measures of BrdU-labeled tumor cells. The second model utilized a chemically-induced (N-methyl-N-nitrosourea MNU) model of rat mammary carcinoma to correlate measures of (18)FISO-1 and FDG uptake with MR-based volumetric measures of tumor growth. In addition, (18)FISO-1 and FDG were used to assess the response of MNU-induced tumors to bexarotene and Vorozole therapy. In the mouse mammary 66 tumors, a strong linear correlation was observed between the (18)FISO-1 tumor: background ratio and the proliferative status (P:Q ratio) of the tumor (R = 0.87). Similarly, measures of (18)FISO-1 uptake in MNU-induced tumors significantly correlated (R = 0.68, P<0.003) with changes in tumor volume between consecutive MR imaging sessions. Our data suggest that PET studies of (18)FISO-1 provide a measure of both the proliferative status and tumor growth rate, which would be valuable in designing an appropriate treatment strategy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A gene expression signature indicative of activated wound responses is common to more than 90% of non-neoplastic tissues adjacent to breast cancer, but these tissues also exhibit substantial ...heterogeneity. We hypothesized that gene expression subtypes of breast cancer microenvironment can be defined and that these microenvironment subtypes have clinical relevance.
Gene expression was evaluated in 72 patient-derived breast tissue samples adjacent to invasive breast cancer or ductal carcinoma in situ. Unsupervised clustering identified two distinct gene expression subgroups that differed in expression of genes involved in activation of fibrosis, cellular movement, cell adhesion and cell-cell contact. We evaluated the prognostic relevance of extratumoral subtype (comparing the Active group, defined by high expression of fibrosis and cellular movement genes, to the Inactive group, defined by high expression of claudins and other cellular adhesion and cell-cell contact genes) using clinical data. To establish the biological characteristics of these subtypes, gene expression profiles were compared against published and novel tumor and tumor stroma-derived signatures (Twist-related protein 1 (TWIST1) overexpression, transforming growth factor beta (TGF-β)-induced fibroblast activation, breast fibrosis, claudin-low tumor subtype and estrogen response). Histological and immunohistochemical analyses of tissues representing each microenvironment subtype were performed to evaluate protein expression and compositional differences between microenvironment subtypes.
Extratumoral Active versus Inactive subtypes were not significantly associated with overall survival among all patients (hazard ratio (HR) = 1.4, 95% CI 0.6 to 2.8, P = 0.337), but there was a strong association with overall survival among estrogen receptor (ER) positive patients (HR = 2.5, 95% CI 0.9 to 6.7, P = 0.062) and hormone-treated patients (HR = 2.6, 95% CI 1.0 to 7.0, P = 0.045). The Active subtype of breast microenvironment is correlated with TWIST-overexpression signatures and shares features of claudin-low breast cancers. The Active subtype was also associated with expression of TGF-β induced fibroblast activation signatures, but there was no significant association between Active/Inactive microenvironment and desmoid type fibrosis or estrogen response gene expression signatures. Consistent with the RNA expression profiles, Active cancer-adjacent tissues exhibited higher density of TWIST nuclear staining, predominantly in epithelium, and no evidence of increased fibrosis.
These results document the presence of two distinct subtypes of microenvironment, with Active versus Inactive cancer-adjacent extratumoral microenvironment influencing the aggressiveness and outcome of ER-positive human breast cancers.
Peroxisome-proliferator-activated receptor γ (PPARγ) is a ligand-activated transcription factor that regulates cell proliferation, differentiation, and apoptosis. In vivo studies were performed to ...evaluate the activities of two thiazolidinedione PPARγ agonists, rosiglitazone and pioglitazone, as inhibitors of oral carcinogenesis in rats. Oral squamous cell carcinomas (OSCC) were induced in male F344 rats by 4-nitroquinoline-1-oxide (NQO; 20 ppm in the drinking water for 10 weeks). In each study, groups of 30 NQO-treated rats were exposed to a PPARγ agonist beginning at week 10 (one day after completion of NQO administration) or at week 17 (7 weeks post-NQO); chemopreventive agent exposure was continued until study termination at week 22 (rosiglitazone study) or week 24 (pioglitazone study). Administration of rosiglitazone (800 mg/kg diet) beginning at week 10 increased survival, reduced oral cancer incidence, and reduced oral cancer invasion score in comparison to dietary controls; however, chemopreventive activity was largely lost when rosiglitazone administration was delayed until week 17. Administration of pioglitazone (500 mg/kg diet beginning at week 10 or 1000 mg/kg diet beginning at week 17) induced significant reductions in oral cancer incidence without significant effects on OSCC invasion scores. Transcript levels of PPARγ and its three transcriptional variants (PPARγv1, PPARγv2, and PPARγv3) were not significantly different in OSCC versus age- and site-matched phenotypically normal oral tissues from rats treated with NQO. These data suggest that PPARγ provides a useful molecular target for oral cancer chemoprevention, and that overexpression of PPARγ at the transcriptional level in neoplastic lesions is not essential for chemopreventive efficacy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Skin cancer is one of the most commonly diagnosed cancers in the United States. Taxifolin reportedly exerts multiple biologic effects, but the molecular mechanisms and direct target(s) of taxifolin ...in skin cancer chemoprevention are still unknown. In silico computer screening and kinase profiling results suggest that the EGF receptor (EGFR), phosphoinositide 3-kinase (PI3K), and Src are potential targets for taxifolin. Pull-down assay results showed that EGFR, PI3K, and Src directly interacted with taxifolin in vitro, whereas taxifolin bound to EGFR and PI3K, but not to Src in cells. ATP competition and in vitro kinase assay data revealed that taxifolin interacted with EGFR and PI3K at the ATP-binding pocket and inhibited their kinase activities. Western blot analysis showed that taxifolin suppressed UVB-induced phosphorylation of EGFR and Akt, and subsequently suppressed their signaling pathways in JB6 P+ mouse skin epidermal cells. Expression levels and promoter activity of COX-2 and prostaglandin E(2) (PGE(2)) generation induced by UVB were also attenuated by taxifolin. The effect of taxifolin on UVB-induced signaling pathways and PGE(2) generation was reduced in EGFR knockout murine embryonic fibroblasts (MEF) compared with EGFR wild-type MEFs. Taxifolin also inhibited EGF-induced cell transformation. Importantly, topical treatment of taxifolin to the dorsal skin significantly suppressed tumor incidence, volume, and multiplicity in a solar UV (SUV)-induced skin carcinogenesis mouse model. Further analysis showed that the taxifolin-treated group had a substantial reduction in SUV-induced phosphorylation of EGFR and Akt in mouse skin. These results suggest that taxifolin exerts chemopreventive activity against UV-induced skin carcinogenesis by targeting EGFR and PI3K.
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